Have you tried screening your FFg GOEX? I found that when I got rid of the clinkers, and the fines, that it burned much cleaner, more consistently, and left no more residue than when I shoot FFFg Goex. The new Goex, made in the new plant in Louisianna,seems to also be Cleaner powder, and better sized at the factory. When we screened a can from a new batch, we got less than 1/2 Tsp. of fines in the powder, compared to 3 oz of FFFg, and 1 oz of FFFFg in some older powder we had.
I also found that using an OP wad increased the chamber pressure, and delayed the movement of the PRB( in my gun) long enough to complete burning.
All this came about because of comments made by some other shooters, in diffirent venues, so, my brother brought his powder screener from Graf & Sons with him when we met a Friendship, we bought some Swiss powder to try, and some more Goex, as we were both running short on our supplies, and then we came home here and screened a couple of cans of powder. He took his Swiss powder home, and has been testing it alongside Goex FFFg in his .40 caliber rifle, and running comparative tests on a Chronograph. Screening both brands of powder( Swiss had fewer "fines"), he found the residue to be the same in both powders. Shooting without an OP wad, he found the swiss powder to give faster velocities( which we expected). However, when he use an OP wad with both powders, the difference in Velocity between the Goex and the Swiss narrowed considerably- down to less than 100 fps. With the OP wad, both powders shot just as clean.
He plans to run the test again, using a wonderlube, instead of a liquid lube. He thought he might have biased his testing of the Goex by using patches that were too damp, and that might account for some of the difference in velocity when he didn't use the OP wad for the base line testing. He said the SDV for both powders dropped when he used the OP wads, indicating that use of an OP wad was beneficial regardless of whether you choose Swiss or Goex powders to shoot.
I am wanting to do that similar kind of test with the new " Cartridge Grade" Goex powder, which I am told is FFFg powder that has been tumbled or rolled to give the granules a more consistent size.
I find your point about shooting the bare ball interesting, in that you were able to continue to shoot bare balls for many shots accurately, without cleaning. That has not been my experience, nor my observation of other shooters using bare balls.
May I ask the bore diameter of the gun you shoot, and the diameter of the balls you shoot? Do you change choice of diameter of balls as the fouling builds in the gun?
I am trying to figure out why I have seen guys in my club fighting to pull balls from their smoothbores that got stuck half way down the barrel when they were shooting the balls bare. One of the shooters claimed he had forgotten to blow down the barrel to soften the fouling, and that is why his ball was stuck. Are you perhaps blowing down the barrel to soften the fouling, too?
I have seen more stuck balls in the cold weather shooting in our Falls, and winters, than in the Hot, Humid days of August, when we hold our club's annual Rendezvous. Perhaps that has something to do with fouling build up? Any ideas?